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The "API" page has been changed by JonathanEllis. http://wiki.apache.org/cassandra/API?action=diff&rev1=31&rev2=32 -------------------------------------------------- === ConsistencyLevel === The `ConsistencyLevel` is an `enum` that controls both read and write behavior based on `<ReplicationFactor>` in your `storage-conf.xml`. The different consistency levels have different meanings, depending on if you're doing a write or read operation. Note that if `W` + `R` > `ReplicationFactor`, where W is the number of nodes to block for on write, and R the number to block for on reads, you will have strongly consistent behavior; that is, readers will always see the most recent write. Of these, the most interesting is to do `QUORUM` reads and writes, which gives you consistency while still allowing availability in the face of node failures up to half of `ReplicationFactor`. Of course if latency is more important than consistency then you can use lower values for either or both. + + All discussion of "nodes" here refers to nodes responsible for holding data for the given key; "surrogate" nodes involved in HintedHandoff do not count towards achieving the requested !ConsistencyLevel. ==== Write ====
